Thermal pile sensing structure integrated with capacitor

ABSTRACT

The present invention discloses a thermal pile sensing structure integrated with one or more capacitors, which includes: a substrate, an infrared sensing unit and a partition structure. The infrared sensing unit includes a first and a second sensing structure. A hot junction is formed between the first and the second sensing structures at a location where the first and the second sensing structures are close to each other. A cold junction is formed between the partition structure and the first sensing structure at a location where these two structures are close to each other. Another cold junction is formed between the partition structure and the second sensing structure at a location where these two structures are close to each other. A temperature difference between the hot junction and the cold junction generates a voltage difference signal. Apart of the partition structure forms at least one capacitor.

CROSS REFERENCE

The present invention is a continuation application of Ser. No.15/917,606, filed Mar. 10, 2018 which is a continuation application ofSer. No. 15/249,214, filed Aug. 26, 2016 which claims priority to TW104137358, filed on Nov. 12, 2015.

BACKGROUND OF THE INVENTION Field of Invention

The present invention relates to a thermal pile sensing structureintegrated with one or more capacitors; particularly, it relates to sucha thermal pile sensing structure which is integrated with a MIMcapacitor or a PIP capacitor, to reduce the chip area and noise.

Description of Related Art

Please refer to FIG. 1 in conjugation with FIG. 2. FIG. 1 shows a blockdiagram of a conventional thermal pile sensing structure which isapplied in a temperature sensing module. FIG. 2 shows a cross sectionview of the conventional thermal pile sensing structure. Theconventional temperature sensing module 100 comprises the conventionalthermal pile sensing structure 10, a noise filter 81, a noise filter 82,a differential amplifier Amp, an analog-to-digital convertor ADC and atemperature sensor 80. The thermal pile sensing structure 10 is capableof generating a voltage difference signal VDS according to a temperaturedifference, whereby the temperature sensing module 100 can sensetemperature. The voltage difference signal VDS (which is a differentialsignal) generated by the thermal pile sensing structure 10 is processedby the noise filter 81 and the noise filter 82, and inputted to thedifferential amplifier Amp. The output (which is also a differentialsignal) of the differential amplifier Amp is inputted to theanalog-to-digital convertor ADC. The analog-to-digital convertor ADCalso receives a temperature signal TS outputted from the temperaturesensor 80. The noise filter 81 and the noise filter 82 includes acapacitor C1 and a capacitor C2, respectively. Besides, the conventionaltemperature sensing module 100 further comprises a capacitor C3. In thisprior art, the capacitor C1, the capacitor C2 and the thermal pilesensing structure 10 are three independent components, which arepackaged separately.

Please refer to FIG. 2. The conventional thermal pile sensing structure10 comprises: a substrate 11; an infrared sensing unit 16; and apartition structure 15. The infrared sensing unit 16 is formed on thesubstrate 11. The infrared sensing unit includes a first sensingstructure 161 and a second sensing structure 162, wherein a hot junctionH is formed between the first sensing structure 161 and the secondsensing structure 162 at a location where the first sensing structure161 and the second sensing structure 162 are close to each other. Thepartition structure 15 surrounds the infrared sensing unit 16. A coldjunction C is formed between the partition structure 15 and the firstsensing structure 161 at a location where the partition structure 15 andthe first sensing structure 161 are close to each other and another coldjunction C is formed between the partition structure 15 and the secondsensing structure 162 at a location where the partition structure 15 andthe second sensing structure 162 are close to each other. Thetemperature difference between the hot junction H and the cold junctionC generates the voltage difference signal VDS. In order for the infraredsensing unit 16 to sense the signal more accurately, this prior artfurther includes a light filter layer 14, which is connected to thethermal pile sensing structure 10 via a bonding layer 13.

If the thermal pile sensing structure 10 is manufactured by a CMOSmanufacturing process, the partition structure 15 usually includes apolysilicon layer Poly 1, plural metal layers M1-M4 (shown to be fourlayers in FIG. 2, but the number of the layers is not necessarily four)and plural via layers V. The first sensing structure 161 and the secondsensing structure 162 are made of the metal layer M1 and the polysiliconlayer Poly 1. Dielectric layers 12 provide insulation between theelectrically conductive structures. The voltage difference signal VDS istransmitted through a transistor circuit 17.

In this prior art, as mentioned-above, the capacitor C1 and thecapacitor C2 are provided between the thermal pile sensing structure 10and the electrical circuit, to filter noises. The capacitor C1, thecapacitor C2 and the thermal pile sensing structure 10 are threeindependent components, which are packaged separately. Hence, this priorart is disadvantageous in that: the overall size of the module islarger, and the manufacturing cost is high.

In view of the above, to overcome the drawbacks in the prior art, thepresent invention proposes a thermal pile sensing structure integratedwith a MIM capacitor a PIP capacitor, which reduces the chip area andalso reduces the noise.

SUMMARY OF THE INVENTION

From one perspective, the present invention provides a thermal pilesensing structure, comprising: a substrate; an infrared sensing unitlocated on or above the substrate, the infrared sensing unit including afirst sensing structure and a second sensing structure, wherein a hotjunction is formed between the first sensing structure and the secondsensing structure at a location where the first sensing structure andthe second sensing structure are close to each other; and a partitionstructure, which surrounds the infrared sensing unit, wherein a coldjunction is formed between the partition structure and the first sensingstructure at a location where the partition structure and the firstsensing structure are close to each other and another cold junction isformed between the partition structure and the second sensing structureat a location where the partition structure and the second sensingstructure are close to each other; wherein the temperature differencebetween the hot junction and the cold junction generates a voltagedifference signal and a part of the partition structure forms at leastone capacitor.

In one embodiment, the at least one capacitor includes aMetal-Insulator-Metal (MIM) capacitor or aPolysilicon-Insulator-Polysilicon (PIP) capacitor.

In one embodiment, the partition structure includes a stack of metallayers and via layers, and the MIM capacitor includes an upper electrodeand a lower electrode which are formed by the metal layers.

In one embodiment, the partition structure includes a stack of metallayers, via layers and polysilicon layers, and the PIP capacitorincludes an upper electrode and a lower electrode which are formed bythe polysilicon layers.

In one embodiment, the thermal pile sensing structure further comprises:a dielectric layer located on or above the substrate, wherein theinfrared sensing unit and the partition structure are formed within thedielectric layer.

In one embodiment, the thermal pile sensing structure further comprises:a bonding layer located on or above the dielectric layer; and a lightfilter layer for filtering out signals other than infrared lightsignals, wherein the light filter layer is connected to the dielectriclayer via the bonding layer.

In one embodiment, the temperature difference between the hot junctionand the cold junction is processed by a transistor circuit to generatethe voltage difference signal, wherein the transistor circuit is formedon the substrate.

From another perspective, the present invention provides a thermal pilesensing structure integrated with one or more capacitors, comprising: asubstrate having a chamber; an infrared sensing unit located on or abovethe substrate, the infrared sensing unit including a first semiconductorstack structure, wherein a hot junction is formed at one end of thefirst semiconductor stack structure which is in the chamber; and apartition structure, which is located at peripheral of the infraredsensing unit, wherein a cold junction is formed between the partitionstructure and the first semiconductor stack structure at a locationwhere the partition structure and the first semiconductor stackstructure are close to each other; wherein a temperature differencebetween the hot junction and the cold junction generates a voltagedifference signal and a part of the partition structure forms at leastone capacitor.

In one embodiment, each of the partition structure and the firstsemiconductor stack structure includes plural layers, and at least oneof the layers of the partition structure and one of the layers of thefirst semiconductor stack structure are at a same elevation level andmade of a same material.

In one embodiment, the at least one capacitor includes aMetal-Insulator-Metal (MIM) capacitor or aPolysilicon-Insulator-Polysilicon (PIP) capacitor.

In one embodiment, the first semiconductor stack structure includes twolayers which are made of different thermal conductive materials andconnected to each other, wherein the thermal conductive materials havedifferent Seebeck coefficients.

In one embodiment, the thermal pile sensing structure further comprises:a second semiconductor stack structure, wherein the hot junction isformed between the first semiconductor stack structure and the secondsemiconductor stack structure at a location where the firstsemiconductor stack structure and the second semiconductor stackstructure are close to each other, and the cold junction is formedbetween the partition structure and the first semiconductor stackstructure at a location where the partition structure and the firstsemiconductor stack structure are close to each other, wherein anothercold junction is formed between the partition structure and the secondsemiconductor stack structure at a location where the partitionstructure and the second semiconductor stack structure are close to eachother.

In one embodiment, each of the partition structure and the secondsemiconductor stack structure includes plural layers, and at least oneof the layers of the partition structure and one of the layers of thesecond semiconductor stack structure are at a same elevation level andmade of a same material.

The objectives, technical details, features, and effects of the presentinvention will be better understood with regard to the detaileddescription of the embodiments below, with reference to the attacheddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of a conventional thermal pile sensingstructure which is applied in a temperature sensing module.

FIG. 2 shows a cross section view of a conventional thermal pile sensingstructure.

FIG. 3 shows a block diagram of a thermal pile sensing structure of thepresent invention which is applied in a temperature sensing module.

FIG. 4 shows a cross section view of the thermal pile sensing structureintegrated with a capacitor according to a first embodiment of thepresent invention.

FIG. 5 shows a cross section view of the thermal pile sensing structureintegrated with a capacitor according to a second embodiment of thepresent invention.

FIG. 6 shows a cross section view of the thermal pile sensing structureintegrated with a capacitor according to a third embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The above and other technical details, features and effects of thepresent invention will be better understood with regard to the detaileddescription of the embodiments below, with reference to the drawings.The drawings as referred to throughout the description of the presentinvention are for illustration only, to show the interrelations betweenthe apparatus and devices, but not drawn according to actual scale.

Please refer to FIG. 3 in conjugation with FIG. 4. FIG. 3 shows a blockdiagram of a thermal pile sensing structure of the present invention,which is applied in a temperature sensing module. FIG. 4 shows a crosssection view of the thermal pile sensing structure according to a firstembodiment of the present invention, wherein the thermal pile sensingstructure is integrated with at least one capacitor. The temperaturesensing module 200 of this embodiment comprises the thermal pile sensingstructure 20, which is integrated with capacitors C1 and C2, adifferential amplifier Amp, an analog-to-digital convertor ADC, and atemperature sensor 80. The temperature sensing module 200 of thisembodiment is different from the conventional temperature sensing module100 in that: in the conventional temperature sensing module 100, theconventional thermal pile sensing structure 10, the noise filter 81 andthe noise filter 82 (i.e., the capacitor C1 and the capacitor C2) arethree independent components, which are packaged separately. However, inthe thermal pile sensing structure 20 of this embodiment, the noisefilter 71 (including the capacitor C1) and the noise filter 72(including the capacitor C2) are integrated into the thermal pilesensing structure 20. In other words, the thermal pile sensing structure20, the capacitor C1 and the capacitor C2 are packaged into one singleintegrated device (the details as to how the capacitor C1 and thecapacitor C2 are integrated into the thermal pile sensing structure 20will be described later).

The operation of the thermal pile sensing structure 20 is based upon theSeebeck effect. The so-called Seebeck effect is thus: the Seebeckcoefficient of an electrically conductive material is a measure of themagnitude of an induced thermoelectric voltage in response to atemperature difference across that electrically conducting material.Therefore, if different temperatures are applied to two ends (e.g., thehot junction H and the cold junction C shown in FIG. 4) of anelectrically conductive material, a voltage difference signal will beinduced. This voltage difference signal can be amplified if differenttypes of electrically conductive materials are used to sense thetemperature difference. In brief, the thermal pile sensing structure 20of this embodiment senses the temperature by generating a voltagedifference signal VDS (as shown in FIG. 3) in response to a temperaturedifference between the hot junction H and the cold junction C (as shownin FIG. 4).

The voltage difference signal VDS (which is a differential signal)generated by the thermal pile sensing structure 20 is processed by theinternally integrated noise filter 71 and the noise filter 72. Theprocessed voltage difference signal VDS is inputted to the differentialamplifier Amp. The signal (which is a differential signal) outputtedfrom the differential amplifier Amp is inputted to the analog-to-digitalconvertor ADC. Optionally but preferably, a capacitor C3 can be disposedbetween the two input ends of the analog-to-digital convertor ADC tostabilize the signal. In addition, the analog-to-digital convertor ADCcan also receive, for example but not limited to, a temperature signalTS outputted by the temperature sensor 80. The operation of thetemperature sensing module 200 is well known to those skilled in theart, so the specific details thereof are not redundantly repeated here.

Please refer to FIG. 4. The thermal pile sensing structure 20 of thisembodiment comprises: a substrate 11, an infrared sensing unit 16, apartition structure 25, a bonding layer 13 and a light filter layer 14.The substrate 11 can be, for example but not limited to, a siliconsubstrate. The substrate 11 has a chamber 11A. The infrared sensing unit16 is formed on or above the substrate 11, for sensing infrared lightsignals. In one embodiment, the infrared sensing unit 16 is configuredto sense far infrared light signals.

In one embodiment, from a cross-section view (e.g., FIG. 4) , theinfrared sensing unit 16 includes at least a first sensing structure 161and a second sensing structure 162. As shown in FIG. 4, the firstsensing structure 161 can be, for example but not limited to, a firstsemiconductor stack structure. In one embodiment, the firstsemiconductor stack structure includes at least two thermal conductivematerials whose Seebeck coefficients are different from each other. Inone embodiment, the first sensing structure 161 includes, from top tobottom, for example but not limited to, a metal layer M1 and apolysilicon layer Poly1. As shown in FIG. 4, the second sensingstructure 162 can be, for example but not limited to, a secondsemiconductor stack structure. In one embodiment, the secondsemiconductor stack structure includes at least two thermal conductivematerials whose Seebeck coefficients are different from each other. Inone embodiment, the second sensing structure 162 includes, from top tobottom, for example but not limited to, a metal layer M1 and apolysilicon layer Poly1. The metal layer M1 and the polysilicon layerPoly1 are both thermal conductive materials, but the Seebeck coefficientof the metal layer M1 is different from the Seebeck coefficient of thepolysilicon layer Poly1. In this embodiment, the first sensing structure161 and the second sensing structure 162 are arranged symmetrically,wherein a hot junction H is formed between the first sensing structure161 and the second sensing structure 162 at a location where the firstsensing structure 161 and the second sensing structure 162 are close toeach other (i.e., at an end of the first sensing structure 161 that iscloser to the chamber 11A, and at an end of the second sensing structure162 that is closer to the chamber 11A). The partition structure 25 islocated at the periphery of the infrared sensing unit 16 and surroundsthe infrared sensing unit 16. A cold junction C is formed between thepartition structure 25 and the first sensing structure 161 at a locationwhere the partition structure 25 and the first sensing structure 161 areclose to each other, and another cold junction C is formed between thepartition structure 25 and the second sensing structure 162 at alocation where the partition structure 25 and the second sensingstructure 162 are close to each other. As mentioned above, the thermalpile sensing structure 20 of this embodiment senses the temperature bygenerating a voltage difference signal VDS in response to a temperaturedifference between the hot junction H and the cold junction C.

Note that the infrared sensing unit 16 does not necessarily include twosensing structures arranged symmetrically (i.e., the first sensingstructure 161 and the second sensing structure 162). In anotherembodiment, the infrared sensing unit 16 may include only one sensingstructure (for example but not limited to the above-mentioned firstsemiconductor stack structure; that is, the first sensing structure161). In this case, a hot junction H is formed at a location that isclose to the chamber 11A. A cold junction C is formed between thepartition structure 25 and the first sensing structure 161 at a locationwhere the partition structure 25 and the first sensing structure 161 areclose to each other. Similarly, as mentioned above, the thermal pilesensing structure 20 of this arrangement can still sense the temperatureby generating a voltage difference signal VDS in response to atemperature difference between the hot junction H and the cold junctionC. More specifically, in one embodiment, from a cross-section view, theinfrared sensing unit 16 may include only one sensing structure, and theinfrared sensing unit 16 is not symmetrical. Or, in another embodiment,from a top view, the sensing structure is a semiconductor stackstructure having a sector or a circle shape, with the hot junction Hbeing a center and the cold junction C being a circumference of thesector or circle. In this case, from the cross-section view (e.g., FIG.4), the infrared sensing unit 16 includes two sensing structures whichare arranged symmetrically, but these two sensing structures, however,are actually two different parts of one same semiconductor stackstructure. All of the above-mentioned embodiments are within the scopeof the present invention. Moreover, the embodiment of FIG. 4 includes adielectric layer 12 which is located on or above the substrate 11. Inone embodiment, the dielectric layer 12 can be made of, for example butnot limited to, silicon oxide (SiO2). The dielectric layer 12 of thisembodiment for example can be used to absorb infrared rays. The infraredsensing unit 16 and the partition structure 25 of this embodiment areformed within the dielectric layer 12.

The bonding layer 13 is formed on or above the dielectric layer 12. Thelight filter 14 is connected to the dielectric layer 12 via the bondinglayer 13. The light filter 14 filters signals other than infrared lightsignals for the thermal pile sensing structure 20.

The light filter 14 allows an infrared light signal emitted or reflectedfrom a certain object (not shown) to pass through. In one embodiment,the thickness of the light filter 14 can be, for example but not limitedto, within a range from 5 μm to 15 μm. In one embodiment, the lightfilter 14 can be made of a material of, for example but not limited to,polyethylene (PE), polypropylene/polypropene (PP) or polyethyleneterephthalate (PET). The light filter 14 can, in addition to filteringout unwanted light signals, prevent dirt from entering into the thermalpile sensing structure 20.

The temperature difference generated by the infrared sensing unit 16 canbe processed by a circuit, to generate the voltage difference signalVDS. Such a circuit can be, for example but not limited to, a transistorcircuit 17 (as shown in FIG. 4) formed on or above the substrate 11.

In one embodiment, the thermal pile sensing structure 20 of thisembodiment can be made by means of a standard CMOS manufacturingprocess. By depositing polysilicon, metals and silicon oxide, andetching them to desired patterns, can form the transistor circuit 17,the infrared sensing unit 16, the partition structure 25 and thedielectric layer 12. In subsequent steps, the substrate 11 can befurther etched by, for example but not limited to, a backside siliconetching step, so as to form the substrate 11 having a chamber 11A asshown in FIG. 4. Next, in subsequent steps, the bonding layer 13 and thelight filter 14 can be formed by bonding.

An important feature of the present invention is that: a part of thepartition structure 25 forms at least one capacitor. More specifically,referring to FIG. 4: the partition structure 25 includes a stack of fourmetal layers M1-M4 (e.g., aluminum), plural via layers V (e.g.,tungsten), and optionally one or more polysilicon layers (in thisembodiment, the polysilicon layer is denoted as Poly1). The number,material, order and layout pattern of the stack may be modified to meetparticular conditions and are not limited to the shown embodiment. Thenumber of the metal layers and the via layers can be different, and themetal layers and the via layers can be made of materials different fromthe above-mentioned materials, and the order and the layout pattern ofthe stack can be varied (e.g., a via layer V can be at the top of thewhole stack). As shown in FIG. 4, in one embodiment, the metal layer M1of the partition structure 25 and the metal layer M1 of the firstsensing structure 161 (i.e., the above-mentioned first semiconductorstack structure) are the same layer (i.e., made by the same step in aCMOS manufacturing process, formed at the same elevation level and madeof the same material). And, the polysilicon layer Poly1 of the partitionstructure 25 and the polysilicon layer Poly1 of the first sensingstructure 161 are the same layer (i.e., made by the same step in a CMOSmanufacturing process, formed at the same elevation level and made ofthe same material). In on embodiment, the metal layer Ml of thepartition structure 25 and the metal layer M1 of the second sensingstructure 162 (i.e., the above-mentioned second semiconductor stackstructure) are the same layer (i.e., made by the same step in a CMOSmanufacturing process, formed at the same elevation level and made ofthe same material). And, the polysilicon layer Poly1 of the partitionstructure 25 and the polysilicon layer Poly1 of the second sensingstructure 162 are the same layer (i.e., made by the same step in a CMOSmanufacturing process, formed at the same elevation level and made ofthe same material).

The above-mentioned metal layers M1-M4 and the via layer V are describedbased upon the general terminology commonly used in a standard CMOSmanufacturing process; that is, the metal layers M1-M4 and the via layerV correspond to the metal layers and the via layer in theinterconnection structure of a semiconductor microelectronic circuit.However, please note that this embodiment further includes a metal layerM3A between the metal layer M3 and the metal layer M4. The metal layerM4, the insulating layer (i.e., a part of the dielectric layer 12) andthe metal layer M3A form a Metal-Insulator-Metal (MIM) capacitor 25A.The metal layer M4 acts as an upper electrode of the MIM capacitor 25Aand the metal layer M3 acts as a lower electrode of the MIM capacitor25A. This MIM capacitor 25A can be used as the above-mentioned capacitorC1 or C2. Thus, the present invention can integrate the capacitor C1and/or the capacitor C2 into the thermal pile sensing structure 20, togreatly reduce the overall area of the temperature sensing module andthe manufacturing cost.

Please refer to FIG. 5, which shows a cross section view of the thermalpile sensing structure according to a second embodiment of the presentinvention. The thermal pile sensing structure 30 of this embodiment issimilar to the thermal pile sensing structure 20 of the firstembodiment, but is different in that: in the thermal pile sensingstructure 30 of this embodiment, as shown in FIG. 5, the partitionstructure 25 includes, in addition to a stack of four metal layers M1-M4(e.g., aluminum) and via layers V (e.g., tungsten), two polysiliconlayers Poly1 and Poly2. The above-mentioned metal layers M1-M4, vialayer V and polysilicon layers Poly1 and Poly2 can be made by a standardCMOS manufacturing process. Similar to the above-mentioned embodiment,the number, material, order and layout pattern of the stack may bemodified to meet particular conditions and are not limited to the shownembodiment. In the embodiment shown in FIG. 5, the polysilicon layersPoly1 and Poly2 form a Polysilicon-Insulator-Polysilicon (PIP) capacitor26B. This PIP capacitor 26B can be used as the above-mentioned capacitorC1 or C2. Thus, the present invention can integrate the capacitor C1and/or the capacitor C2 into the thermal pile sensing structure 30, togreatly reduce the overall area of the temperature sensing module andthe manufacturing cost.

Please refer to FIG. 6, which shows a cross section view of the thermalpile sensing structure according to a third embodiment of the presentinvention. The thermal pile sensing structure 40 of this embodiment issimilar to the thermal pile sensing structures 20 and 30 of theabove-mentioned embodiments, but is different in that: in the thermalpile sensing structure 40 of this embodiment, as shown in FIG. 6, thepartition structure 25 includes both a MIM capacitor 25A and a PIPcapacitor 26B. That is, the thermal pile sensing structure 40 of thisembodiment include not only a MIM capacitor 25A but also a PIP capacitor26B. the configuration of this embodiment can produce a relativelylarger capacitor in a relatively smaller area.

As compared to the prior art, the thermal pile sensing structure 20, 30and 40 of the foregoing embodiments remove external capacitors andtherefore can effectively reduce the area of temperature sensing module.Besides, because the capacitors of the foregoing embodiments areintegrated within the thermal pile sensing structure instead of beingexternal components, the signal transmission noise can be reduced, whichis also superior to the prior art.

The present invention has been described in considerable detail withreference to certain preferred embodiments thereof. It should beunderstood that the description is for illustrative purpose, not forlimiting the scope of the present invention. An embodiment or a claim ofthe present invention does not need to achieve all the objectives oradvantages of the present invention. The title and abstract are providedfor assisting searches but not for limiting the scope of the presentinvention. Those skilled in this art can readily conceive variations andmodifications within the spirit of the present invention. For example,the numbers of the metal layers and the via layers can be modified toany other numbers instead of the numbers in the shown embodiments. Inview of the foregoing, the spirit of the present invention should coverall such and other modifications and variations, which should beinterpreted to fall within the scope of the following claims and theirequivalents.

1. A thermal pile sensing structure, comprising: a substrate, having asurface plane (X-Y plane) and a normal direction (Z-direction) which isperpendicular to the surface plane; an infrared sensing unit locatedabove the substrate; and a partition structure, which extends in theZ-direction and around the infrared sensing unit; wherein at least onehot junction and at least one cold junction are parts of the infraredsensing unit and/or the partition structure; wherein a temperaturedifference between the hot junction and the cold junction generates avoltage difference signal and a part of the partition structure has atleast one capacitor having an upper electrode and a lower electrode,wherein the upper electrode is located at a higher level than the lowerelectrode in the Z-direction.
 2. The thermal pile sensing structure ofclaim 1, wherein the at least one capacitor includes aMetal-Insulator-Metal (MIM) capacitor or aPolysilicon-Insulator-Polysilicon (PIP) capacitor.
 3. The thermal pilesensing structure of claim 2, wherein the partition structure includes astack of metal layers and via layers, and the MIM capacitor includes theupper electrode and the lower electrode which are formed by the metallayers.
 4. The thermal pile sensing structure of claim 2, wherein thepartition structure includes a stack of metal layers, via layers andpolysilicon layers, and wherein the PIP capacitor includes the upperelectrode and the lower electrode which are formed by the polysiliconlayers.
 5. The thermal pile sensing structure of claim 1, furthercomprising: a dielectric layer located on or above the substrate,wherein the infrared sensing unit and the partition structure are formedwithin the dielectric layer.
 6. The thermal pile sensing structure ofclaim 5, further comprising: a bonding layer located on or above thedielectric layer; and a light filter layer for filtering out signalsother than infrared light signals, wherein the light filter layer isconnected to the dielectric layer via the bonding layer.
 7. The thermalpile sensing structure of claim 1, wherein the temperature differencebetween the hot junction and the cold junction is processed by atransistor circuit to generate the voltage difference signal, thetransistor circuit being formed on the substrate.